Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 202030

Area Forecast Discussion
National Weather Service Saint Louis MO
230 PM CST Mon Nov 20 2017

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 229 PM CST Mon Nov 20 2017

No significant weather is expected this evening. Wind gusts will
subside tonight with the loss of diurnal mixing, however the
sustained winds will likely remain near 10-15 mph overnight due to
the modest pressure gradient across the region.

A low pressure system will skirt the US/Canadian border
tonight/tomorrow and drive a cold front through the region. Parts of
northeast MO and west central IL may experience only a limited
diurnal rise in the morning hours before temperatures become nearly
steady and start falling again after fropa. Elsewhere, many
locations will experience falling temperatures during the afternoon
hours after the front has moved through the area. Model solutions
show that the front will have moved through the CWA by 00z Wed.
Although a stray sprinkle is possible tomorrow, the limited moisture
and forcing suggest that widespread measurable precipitation is
unlikely. The better opportunity for precipitation will be farther
north and east where there is deeper moisture and move overlap with
upper forcing for ascent.


.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 229 PM CST Mon Nov 20 2017

Roller coaster temperatures to be the main theme through the
extended forecast period. Surface ridge builds into region Tuesday
night with decent CAA. So with clear skies and light winds, will see
lows in the low to mid 20s.  Wednesday will be the coldest day this
week with highs only in the upper 30s to mid 40s.

Surface ridge to begin moving off to the east Wednesday night so
will see southerly winds return to the area briefly before next cold
front slides through on Thanksgiving. Fortunately this frontal
passage should be a dry one, as main energy and moisture remain to
the north of us over the Great Lakes region. Will still see warmer
temps on Thursday, in the upper 40s to mid 50s.

Even warmer temps expected on Friday with highs in the mid 50s to
mid 60s, 5 to 10 degrees above normal for this time of year. Then
next in series of weak cold fronts to slide through region Friday
night. Little or no precipitation is expected with this one as well
with main energy to our north once again. Despite dry passage with
this front, system to continue digging to our east with deep trof
aloft and upper ridge to our west. So will see decent surface ridge
build in with temps dipping down into the 40s everywhere by Sunday.
Then pattern continues with moderating temps by next Monday.


.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1109 AM CST Mon Nov 20 2017

VFR flight conditions are expected for the next 24-30 hours,
however there are several wind considerations despite the lack of
cig/vis restrictions. Gusty southwest surface winds at TAF
issuance will diminish overnight and back slightly to the south,
but SW to WSW winds aloft will increase markedly after 21/00z.
This will lead to LLWS after approximately 21/03z at all
terminals. Surface winds will then veer and become westerly ahead
of an approaching cold front. Surface winds will become
northwesterly after the front has moved through the region late in
the TAF period.


Saint Louis     44  55  26  41 /   0   5   0   0
Quincy          41  48  22  39 /   0   5   0   0
Columbia        42  54  23  42 /   0   0   0   0
Jefferson City  42  56  24  43 /   0   0   0   0
Salem           40  54  26  40 /   0   5   0   0
Farmington      38  57  25  42 /   0   5   0   0



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